fix: gcs_object_metadata_client can't handle required_tasks (#467)

* fix: required_tasks error

* fix: delete unnecessary function

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* test: nested required_task output

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: kitagry

gokart/gcs_obj_metadata_client.py

@@ -98,8 +98,6 @@ def _get_patched_obj_metadata(
         if not isinstance(metadata, dict):
             logger.warning(f'metadata is not a dict: {metadata}, something wrong was happened when getting response when get bucket and object information.')
             return metadata
-        if not task_params and not custom_labels:
-            return metadata
         # Maximum size of metadata for each object is 8 KiB.
         # [Link]: https://cloud.google.com/storage/quotas#objects
         normalized_task_params_labels = GCSObjectMetadataClient._normalize_labels(task_params)
@@ -117,18 +115,17 @@ def _get_patched_obj_metadata(
 
     @staticmethod
     def _get_serialized_string(required_task_outputs: FlattenableItems[RequiredTaskOutput]) -> FlattenableItems[str]:
-        def _iterable_flatten(nested_list: Iterable) -> Iterable[str]:
-            for item in nested_list:
-                if isinstance(item, Iterable):
-                    yield from _iterable_flatten(item)
-                else:
-                    yield item
-
-        if isinstance(required_task_outputs, dict):
+        if isinstance(required_task_outputs, RequiredTaskOutput):
+            return required_task_outputs.serialize()
+        elif isinstance(required_task_outputs, dict):
             return {k: GCSObjectMetadataClient._get_serialized_string(v) for k, v in required_task_outputs.items()}
-        if isinstance(required_task_outputs, Iterable):
-            return list(_iterable_flatten([GCSObjectMetadataClient._get_serialized_string(ro) for ro in required_task_outputs]))
-        return [required_task_outputs.serialize()]
+        elif isinstance(required_task_outputs, Iterable):
+            return [GCSObjectMetadataClient._get_serialized_string(ro) for ro in required_task_outputs]
+        else:
+            raise TypeError(
+                f'Unsupported type for required_task_outputs: {type(required_task_outputs)}. '
+                'It should be RequiredTaskOutput, dict, or iterable of RequiredTaskOutput.'
+            )
 
     @staticmethod
     def _merge_custom_labels_and_task_params_labels(

test/test_gcs_obj_metadata_client.py

@@ -7,6 +7,7 @@
 
 import gokart
 from gokart.gcs_obj_metadata_client import GCSObjectMetadataClient
+from gokart.required_task_output import RequiredTaskOutput
 from gokart.target import TargetOnKart
 
 
@@ -113,6 +114,32 @@ def test_get_patched_obj_metadata_with_conflicts(self):
         self.assertEqual(got['created_by'], 'hoge fuga')
         self.assertEqual(got['param1'], 'a' * 10)
 
+    def test_get_patched_obj_metadata_with_required_task_outputs(self):
+        got = GCSObjectMetadataClient._get_patched_obj_metadata(
+            {},
+            required_task_outputs=[
+                RequiredTaskOutput(task_name='task1', output_path='path/to/output1'),
+            ],
+        )
+
+        self.assertIsInstance(got, dict)
+        self.assertIn('__required_task_outputs', got)
+        self.assertEqual(got['__required_task_outputs'], '[{"__gokart_task_name": "task1", "__gokart_output_path": "path/to/output1"}]')
+
+    def test_get_patched_obj_metadata_with_nested_required_task_outputs(self):
+        got = GCSObjectMetadataClient._get_patched_obj_metadata(
+            {},
+            required_task_outputs={
+                'nested_task': {'nest': RequiredTaskOutput(task_name='task1', output_path='path/to/output1')},
+            },
+        )
+
+        self.assertIsInstance(got, dict)
+        self.assertIn('__required_task_outputs', got)
+        self.assertEqual(
+            got['__required_task_outputs'], '{"nested_task": {"nest": {"__gokart_task_name": "task1", "__gokart_output_path": "path/to/output1"}}}'
+        )
+
 
 class TestGokartTask(unittest.TestCase):
     @patch.object(_DummyTaskOnKart, '_get_output_target')